The site consists of 44 acres along state Route 14 two-and-a-half miles northwest of Salem on the Columbiana-Mahoning county line and cleanup is expected to cost $19 million.

The Superfund, created in December of 1980, is the federal government's program to clean up the nation's most polluted hazardous waste sites.

For 12 years, between 1961 and 1973, Nease Chemical produced various household cleaning compounds, fire retardants and pesticides-some of which included what the EPA called an "uncommon chemical" - mirex.

Nease Chemical used unlined ponds to treat waste from the manufacturing process and hazardous substances seeped into the soil and ground water from the ponds.

The waste was also placed in buried drums that eventually leaked.

Consequently, the soil was contaminated with mirex and the groundwater was contaminated by a group of chemicals called volatile organic compounds.

Surface water runoff from the waste treatment ponds flowed into nearby feeder creek tributaries that run through the site causing pollution in the Middle Fork of Little Beaver Creek which is east of the site, the EPA said.

Mirex has not been manufactured in the U.S. since 1978 when it was banned and the Nease site was placed on the Superfund list 29 years ago, in 1983.

Ruetgers Organics Corp. acquired the Nease property in 1977 but never operated at the site.

The EPA signed a Record of Decision in 2008 detailing the soil and sediment (mud) cleanup in the creek while working with Ruetgers to ensure that plans are developed and the creeks are cleaned up.

The cleanup design had been expected in 2011 and the last update was in April 2010 with the next set of procedures scheduled for this year.

Those included removal of the most contaminated sediment in the Middle Fork of Little Beaver Creek; removal of Feeder Creek sediment; removal of the most contaminated floodplain surface soil; and disposal of soil and sediment at the old Nease plant, where it will be covered with clean soil.

The EPA detailed that aspect, explaining that when the sediment is moved to the Nease site, it will be dried out and placed with contaminated soil from Nease.

It will be covered with clean soil and monitored to ensure that it doesn't move or leak. Contaminated soil currently on the Nease property will be handled in a similar way, according to a 2005 cleanup decision.

"Dealing with environmental matters (such as contaminated soil and sediment) locally is a more responsible approach than sending it someplace else where it becomes another community's problem," the EPA said.

New samples of fish, sediment (mud) and water were taken from the creek in late 2005 and from fish tissue in 2005 and 2009.

Floodplains were sampled in 2006 and the information was used to develop the 2008 cleanup decision. Fish tissue samples were taken again in 2010 and those results are included in designing a long-term monitoring strategy.

In 2006, treatment with "nanoscale zero-valent iron" began at the site.

The treatment (also called NZVI) was started in one of the most contaminated spots in the ground water.

"NZVI is an innovative technology that injects microscopic particles of specially treated iron into the ground water," the EPA said.

The tiny particles will chemically clean deep ground water.

At the time, the EPA said, "This innovative technology will allow the particles to flow with the ground water while cleaning the underground aquifer as they reach into the smallest cracks in the bedrock under the site."